A circuit board refers to a printed circuit board inserted into a slot of a backplane, and usually includes: a service board, a switch board and a main control board. One inserted into a service slot of the backplane is called a service board, one inserted into a switch slot of the backplane is called a switch board, and one inserted into a main control slot of the backplane is called a main control board. The switch board includes a switch chip, and in a centralized switching system, data signals on the circuit boards except the switch board may be connected to the switch chip of the switch board, thereby implementing data interchanging between each slot. In a full-interconnect system, data of each service slot may be connected directly. The main control board is a circuit board taking a part in control and management, may be existed independently, and may also be combined with the switch board.
With the increase of signal rates and due to limitation of dielectric loss, crosstalk and power consumption, it is more and more difficult to adopt a conventional electric backplane. The optical backplane system has advantages such as low loss, low crosstalk, high density and independence between a channel characteristic and the rate. Therefore, compared with the electric backplane solution, the optical backplane solution may reach a higher system capacity, and may implement smooth upgrading.
A communication system is usually installed on a rack, and the backplane is perpendicular to an installation surface, so that an operator inserts and pulls out a circuit board conveniently. A connector is installed at each slot of the backplane where multiple connectors may be installed sometimes, and the connector is used to connect the circuit board and the backplane. When the backplane is fully configured, all the slots are inserted with the circuit boards. When the backplane is not fully configured, some slots are inserted with the circuit boards while the rest slots are not inserted with the circuit boards. In an optical backplane system, if the system is in a working state and the circuit board is pulled out from the optical backplane, optical signal leakage may be resulted on the optical connector at the slot where the circuit board is pulled out, and the leakage just faces the operator directly, which may cause injuries to the operator, especially to eyes.